In dental treatment, as is shown in patent document 1, because of the easiness of putting on or removing, various dental attachments which utilize magnetic attractive force have been proposed.
A dental attachment 91 housed a magnetic body is, as is shown in FIG. 19, embedded in dental base 810 fixed a denture 81. On the tooth root side, a keeper 92 made of a soft magnetic material is embedded in a root cap 82 or an implant (FIG is abbreviated). By this, the denture housed the dental attachment 91 can be fixed to the keeper 92 by the magnetic attractive force.
The dental attachment 91 is fixed to the dental base 810 with adhesive of room temperature polymerization resin etc. The fitting strength greatly influences the endurance of the whole denture 81 which houses the dental attachment 91. Therefore, to improve the fitting strength between the dental attachment and the dental base, making a part protruding radially outward from the outer peripheral surface thereof, a so-called under cut effect thereof is proposed (See patent document 2).
[patent document 1]: Japanese Unexamined Patent Application Publication No. 7-136190
[patent document 2]: Japanese Unexamined Utility Model Application Publication No. 6-86715
When the dental attachment is fixed in the dental base, it is necessary to prepare an adhesive in a hole of the dental base beforehand, push the dental attachment by giving a stress on it and make the adhesive go around as far as the outer peripheral surface. In contrast, when only a protruding part is made, as in the prior art, the protruding part prevents the fluidity of adhesive and without exerting enough under cut effect, the connecting strength can not be improved much.
Still, in this structure, when the turning force to turn relatively is added between the dental base and the dental attachment, the problem that the dental attachment turns more easily relative to the dental base is generated because the outer peripheral surface of the dental attachment and the protruding part are constructed in a concentric configuration.
To solve prior problems, the present invention provides a dental attachment that is greatly improved over prior objects in fixing strength and can more effectively prevent turning to the dental base.